1. Field of the Invention
The invention relates to a valve cartridge comprising a rotating disk and a fixed disk, both configured to control the flow of fluid through the valve cartridge; and, more particularly, to the relative orientation of elements in the cartridge.
2. Description of the Related Art
Fluid valves using valve stacks are widely known and appear in various configurations, such as in-line valves, diverter valves, and hydrants, to name a few. A typical valve stack comprises a fixed disk and a rotating disk, both of which are configured to control the flow of fluid through the valve. Ceramic disks are preferred for their durability, wearability and lack of corrosion. Almost all ceramic valves comprise a xe2x80x9cstack-upxe2x80x9d that traditionally includes one or more O-rings, a fixed ceramic disk, a rotating ceramic disk, and a bearing in contact with the rotating ceramic disk. The stack-up is typically contained within a valve body, which defines the various inlets and outlets through which fluid can enter and exit the valve. The stack-up is typically under pressure (the stack-up pressure), along a given axis, which must be sufficient to prevent fluid from leaking between the interface of the disks while having a rotating force less than a predetermined value. Typically, the stack-up pressure is applied by securing a valve body holding the stack-up against a compression seat, or securing a retainer to the end of the valve body as disclosed in U.S. Pat. No. RE 35,545. The rotating force is the force that a user must supply to the handle of the valve to rotate the rotating disk with respect to the fixed disk to turn the valve through its various operating positions.
Obviously, the more elements introduced into the stack, the more tolerance errors appear that affect the stack-up pressure. This is particularly critical with the tolerances between the two ceramic disk elements. The two mating surfaces of the ceramic disks must be within close enough tolerances to effectively seal fluid from passing between them and allow fluid to pass only through the intended passages. However, once the stack-up pressure is applied, the two mating surfaces will sometimes actually stick together in a condition called xe2x80x9csticksionxe2x80x9d wherein the two ceramics cannot be rotated relative to each other, even if the stack-up pressure is relieved. Obtaining and maintaining the proper stack-up pressure and accommodating tolerance errors in the stack-up are problems for all valves using a ceramic stack-up.
There is a need for a ceramic valve that reduces tolerance errors in the stack-up and provides better control over the stack-up pressure.
The invention relates to a valve cartridge for controlling the flow of fluid from a fluid source to a fluid outlet. In one aspect of the invention, the valve cartridge comprises a valve body having a longitudinal axis. A first disk is mounted to the valve body on the longitudinal axis such that it is axially and radially immovable relative to the valve body. A second disk is mounted to the valve body on the longitudinal axis and maintained in an axially facing relationship with the first disk. The second disk is rotatable relative to the valve body and to the first disk.
Each of the first and second disks is configured to permit fluid flow through the valve body when the second disk is in a first position, and to bar fluid flow through the valve body when the second disk is in a second position. A biasing element is disposed between the valve body and the second disk to bias the second disk against the first disk along the longitudinal axis.
Preferably, the valve cartridge further has a first annular shoulder and the first disk is held against the first annular shoulder by a retainer. Alternatively, the first disk is the retainer, simply secured against the first annular shoulder. The valve body can have a second annular shoulder against which the biasing element bears.
Preferably, the biasing element is a resilient seal, which typically would be an O-ring. In some embodiments, a stem will extend into the valve body and be operably connected to the rotatable disk to effect selective rotation of the second disk relative to the first disk. Preferably, the stem will extend axially from the valve body, but the stem can also extend radially from the valve body.
Typically, the disks will be ceramic disks and the hardness and size of the resilient seal is selected to control the biasing force applied to the second disk.
In another aspect of the invention, a conventional valve cartridge is of the type having a valve body with first and second ceramic disks disposed in facing relationship. The first ceramic disk is mounted to the body in a manner to prohibit rotatable movement of the first disk and the second disk is mounted to the valve body in a manner to permit rotatable movement relative to the valve body and to the first disk. The invention lies in the improvement wherein the first ceramic disk is fixed in the valve body to prohibit axial movement of the ceramic disk relative to the valve body and to the second ceramic disk.
Preferably, the valve cartridge further has a first annular shoulder and the first disk is held against the first annular shoulder by a retainer. Alternatively, the first disk is the retainer, simply secured against the first annular shoulder.